Related art alarm devices known as home alarm devices have a function to detect abnormal conditions, such as a fire and gas leak, in the home and warn of the abnormal conditions with sound or other means. Recent homes have two or more alarm devices installed therein to monitor the occurrence of abnormal conditions, such as a fire, in each room.
In such a home with two or more alarm devices installed therein, a user in a room other than the room where an abnormal condition is occurring sometimes cannot hear alarm sound. As a result, a disaster, such as a fire, may spread. Consequently, there is proposed in which the alarm devices is connected in cable mutually when one of the hard-wired alarm devices detects fire, that alarm device transmits signals to others to make them simultaneously output an alarm sound, thereby implementing a interlocking alarm (see, for example, the following Patent Document 1).
However, hard-wired alarm devices require wiring works and are thus costly. This problem can be solved by adopting wireless alarm devices. Since the latest ICs for radio circuits have reduced in power consumption, the alarm devices are guaranteed with longer, e.g., over five years, practical battery life even if the alarm devices are always ready for receiving signals from other alarm devices in order to enable reception of signals from other alarm devices. Thus, an environment for practical wireless alarm devices is being completed.
In the related art alarm systems, when one of the two or more hard-wired alarm devices detects a fire, the alarm device which detected fire, i.e., a interlocking source, sounds an alarm different from that output from other alarm devices which received a fire signal, i.e., interlocking destinations. For example, the interlocking source alarm device which detected fire continually outputs a voice message “(sound of siren) Fire alarm device was activated. Check it out.” On the contrary, the interlocking destination alarm device continually output a voice message “(sound of siren) Another alarm device was activated. Check it out.” A red light of the interlocking source alarm device is flashing while red light of the interlocking destination alarm device is blinking. This means that a user can distinguish the interlocking source alarm device from the interlocking destination alarm device by confirming indication of the red light.
An alarm device includes an alarm stop switch which is also used as a check switch. When a switch is operated with, for example, a pulling string while the alarm device is outputting an alarm, output of the alarm can be stopped. In the hard-wired alarm devices, when the alarm stop switch of the interlocking source alarm device which detected fire is operated, the alarm sound output from all the alarm devices stops. When the alarm stop switch of the interlocking destination alarm device is operated, the alarm sound of that alarm device stops.
When the output of alarm from the interlocking source alarm device is stopped, if, for example, smoke, which indicates a fire, remains all the alarm devices output alarms again after a predetermined period of time elapsed.    [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2007-094719